Rockwell Automation Allen-Bradley PowerFlex 700AFE, Руководство пользователя

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Rockwell Automation Publication 20Y-UM001F-EN-P - April 2017 15
Preface
Active current and reactive currents are calculated from the three input phase
current measurements (I
L1
, I
L2
, and I
L3
) as shown in Figure 3 . The DC voltage
controller is a PI type regulator. A DC voltage reference sets the value of the
DC link voltage to be maintained. It is compared to measured DC voltage to
obtain a DC voltage error as the input for the DC voltage controller.
The output of the DC voltage controller is the active current reference, which
is compared to the measured active current. The error between them is the
input for the active current controller. The output of the active current
controller changes the modulation index and controls the inverter voltage.
The reactive current reference can be used for reactive power compensation. A
positive reactive current reference indicates inductive and a negative reactive
current reference indicates capacitive reactive power compensation. The
default value of the reactive current reference parameter is zero. The set value
of the reactive current reference is compared to its measured value and the error
is fed to the PI regulator. The PI regulator is also referred to as the
synchronizing controller because its function is to keep the inverter
synchronized with line supply. The frequency reference to the AFE is derived
from the reactive current controller output. Normally the active current Kp,
active current Ki, reactive current Kp, and reactive current Ki default values of
the two current controllers are satisfactory with the standard LCL filter. Do
not change the default values.
Figure 3 - AFE Block Diagram
I
L1
3
2
_ _
_
PI PI
PI PD
DC Volt Kp
DC Volt Ki
Reactive Curr Kp
Reactive Curr Ki
Active Curr Kp
Active Curr Ki
Cartesian
Polar
I Alpha
I Beta
I
L2
I
L3
Park Transform
Reactive Current
Active Currrent
Modulation Index
Modulator Voltage Angle
Active Current Ref
Active Currrent
DC Volt Measured
DC Volt Reference
Reactive Current Ref
Reactive Current
Freq Reference